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My concern was whether or not the 12v battery was being charged in this mode(ice on charging hybrid battery pack). Now when the car is plugged in at home or wherever, the 12v is not charged or maintained during that process.
Understood. Some people mistake Charge Mode for Hold Charge mode The button is labeled "Hold Charge" because you have to hold it for a second to put it in Charge Mode.
Hello All, I don't have any experience with the plugin hybrid, as mine is a 2023 350h. But what I can tell you is that based on my experience, those who are experiencing dead battery with 350h, probably are having a batch of bad batteries. Me and my friend bought two 350h premium build in May of 2023 and have not had any dead battery issue since then. He uses his daily. I use mine either once a week or once every two weeks sitting in my garage. I have never seen a low battery message or never had dead battery. My conclusion based on my experience is that there have been a batch of bad batteries built during the pandemic and Lexus is suffering from those bad batches. Also as I mentioned in my previous messages, I have set my settings to keep the radio on till i open the door, i do not keep it in ACC mode, and set to turn off the headlight as soon as I open the door. Just have the Lexus dealer replace the battery. It would be crazy to buy a $70 K car and having to have extra charger in the trunk. Again, just sharing my experience.
It could also be a combination of some marginal batteries combined with a suboptimal charging algorithm. Otherwise, I'd expect to see the same issues in all RXs.
It could also be a combination of some marginal batteries combined with a suboptimal charging algorithm. Otherwise, I'd expect to see the same issues in all RXs.
There's always the power distribution from the battery in the back to the ICE in the front (and any fuse boxes up front) - undersized wiring or routing issues (potential cable pinching kinds of things).
Has anyone that had a battery replaced under warranty run into issues a second time?
I suppose, “stretching it” is any period of inactivity that causes a vendors new battery to go flat. As a frequent traveller, leaving a car at the airport for 2-3 weeks has never left me feeling like I better call the Automobile Association for a boost. I don’t know of any car more electrically demanding than my Tesla, but as far back as 2016 when I got the car, it shuts various systems Down to preserve power.
it’s not rocket science nor would it be a successful marketing strategy to offer a trickle charger as an option for those who “don’t drive their car every day”.
I guess ‘reasonable’ is what ever you want to make it, but let us know how it goes if a cold snap hits and you need a jump! 😉
My 2024 RX450h+ was draining the 12 V battery whenever it sat for a few days. I bought a battery monitor on Amazon that tracks battery voltage and downloads data to the phone. I noticed a cyclical draining of the battery when the vehicle was off. I measured fuse voltages (vehicle off, doors latched) and found the drain was thru fuse ECU-DCC No. 3. I put a fuse extender in and monitored the current thru this fuse. (Fig. Below). Something was evidently turning on and off continuously (vehicle off) and drawing a lot of current. One of the items on this circuit is the Bluetooth Digital Key receiver assembly. (The Digital Key system uses an App on the cell phone to lock/unlock doors and even drive the vehicle without the key fob.) By chance I noticed that the cyclical discharging of the battery was triggered by the garage door opener! (See Fig. Below). It seems the Bluetooth Digital Key receiver was responding to the garage door opener, cycling on and off and discharging the battery. When I disabled the Digital Key system in the car (Settings -> Info & Security -> Enable Digital Keys -> OFF), the problem went away! I’m still able to use the Lexus App to unlock/lock the car, and see info about the vehicle (linking to it through cell phone or WiFI, I guess). But beware the Digital Key—it seems to be a source of serious parasitic battery drain.
Last edited by SMartin; 04-02-24 at 01:41 PM.
Reason: Forgot to mention something.
My 2024 RX450h+ was draining the 12 V battery whenever it sat for a few days. I bought a battery monitor on Amazon that tracks battery voltage and downloads data to the phone. I noticed a cyclical draining of the battery when the vehicle was off. I measured fuse voltages (vehicle off, doors latched) and found the drain was thru fuse ECU-DCC No. 3. I put a fuse extender in and monitored the current thru this fuse. (Fig. Below). Something was evidently turning on and off continuously (vehicle off) and drawing a lot of current. One of the items on this circuit is the Bluetooth Digital Key receiver assembly. (The Digital Key system uses an App on the cell phone to lock/unlock doors and even drive the vehicle without the key fob.) By chance I noticed that the cyclical discharging of the battery was triggered by the garage door opener! (See Fig. Below). It seems the Bluetooth Digital Key receiver was responding to the garage door opener, cycling on and off and discharging the battery. When I disabled the Digital Key system in the car (Settings -> Info & Security -> Enable Digital Keys -> OFF), the problem went away! I’m still able to use the Lexus App to unlock/lock the car, and see info about the vehicle (linking to it through cell phone or WiFI, I guess). But beware the Digital Key—it seems to be a source of serious parasitic battery drain.
Thanks, although I haven't had any battery issues, I'm going to disable the digital key system in the car settings. I have no use for the unreliable digital key.
SMartin....You are one sharp guy and I thank you for this info. Another piece in the puzzle. BUT....in both of our two 450h+ models, neither of us opted to use the digital key, yet the 12v battery in my RX croaked about a week ago. All is well now, after I put a trickle charger on it and I will monitor things a bit more closely in the future but, for me....the mystery continues.
Thanks, although I haven't had any battery issues, I'm going to disable the digital key system in the car settings. I have no use for the unreliable digital key.
SMartin....You are one sharp guy and I thank you for this info. Another piece in the puzzle. BUT....in both of our two 450h+ models, neither of us opted to use the digital key, yet the 12v battery in my RX croaked about a week ago. All is well now, after I put a trickle charger on it and I will monitor things a bit more closely in the future but, for me....the mystery continues.
Same story here, our new 450h+ has already left us stranded. Installed a 12v battery monitor and have watched it slowly lose charge every day until critically low necessitating an overnight trickle charge. We drive it daily and 2 hours a day two of the days a week. On our most recent longer trip, the battery went from 12.5v before to 12.3v afterward.
Has anyone taken their car in for resolution of this? I feel a simple battery swap will not be the solution as there appears to be a parasitic draw and insufficient charging happening. I’ve disabled the digital key with no change.
Same story here, our new 450h+ has already left us stranded. Installed a 12v battery monitor and have watched it slowly lose charge every day until critically low necessitating an overnight trickle charge. We drive it daily and 2 hours a day two of the days a week. On our most recent longer trip, the battery went from 12.5v before to 12.3v afterward.
Has anyone taken their car in for resolution of this? I feel a simple battery swap will not be the solution as there appears to be a parasitic draw and insufficient charging happening. I’ve disabled the digital key with no change.
Its good to see confirmation that disabling the digital key did not resolve the problem. Although it could be the Connected Services and Bluetooth proximity sensors to the key fob causing the parasitic drains as well, in particular scenarios.
I had researched the longer-in-field reliability (2+ years) of the latest generation NX450h+ and NX350h field reliability before going for the RX450h+ - and the NX's have the exact same battery problem. So its systemic - but worsened by at least a few factory-defect batteries.
In the linked thread - at least a couple folks reported that replacing with a "bigger battery" fixed their problem. I take that to mean, ones with more reserve capacity. Here in the RX forums, WellsB narrowed down to a Odyssey battery that would fit the bill, literally by fitting into the stock battery's space. However, I don't know if any RX owner actually replaced their stock battery with an Odyssey to find their problems go away. If someone's willing to try, that'd be great (of course, it would be out of pocket cost vs. dealer replacing under warranty) - assuming the dealer-replaced batteries leave the problem open.
Based on the measurements I made of my OEM battery, which are
9" 3/8 L
7" or 6" 7/8 W
7" 1/2 H
(not exact because I left the battery in the vehicle, but pretty close)
Great idea to replace the OEM Lexus battery with an Odyssey AGM battery. I’m thinking you could even go up one size to the Odyssey ODP-AGM48 H6 L3. This has the same height and width as the H5 L2 you cite, but is 1.5” longer. The battery tray in the RX450h+ looks like it would accommodate this longer battery. This would give you an increased capacity of 70 Ah, versus the 60 Ah of the OEM battery. Plus the advantages of being an AGM versus the OEM FLA battery. Do you think this would work? Do you need to adjust anything in the charging circuit to accommodate an AGM battery?
03-28-24, 07:48 AM
